1 files changed, 93 insertions, 0 deletions
diff --git a/lib/sqfs/meta_writer.c b/lib/sqfs/meta_writer.c
new file mode 100644
index 0000000..95092d5
--- /dev/null
+++ b/lib/sqfs/meta_writer.c
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "meta_writer.h"
+#include "squashfs.h"
+#include "util.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+
+meta_writer_t *meta_writer_create(int fd, compressor_t *cmp)
+{
+	meta_writer_t *m = calloc(1, sizeof(*m));
+
+	if (m == NULL) {
+		perror("creating meta data writer");
+		return NULL;
+	}
+
+	m->cmp = cmp;
+	m->outfd = fd;
+	return m;
+}
+
+void meta_writer_destroy(meta_writer_t *m)
+{
+	free(m);
+}
+
+int meta_writer_flush(meta_writer_t *m)
+{
+	ssize_t ret, count;
+
+	if (m->offset == 0)
+		return 0;
+
+	ret = m->cmp->do_block(m->cmp, m->data + 2, m->offset);
+	if (ret < 0)
+		return -1;
+
+	if (ret > 0) {
+		((uint16_t *)m->data)[0] = htole16(ret);
+		count = ret + 2;
+	} else {
+		((uint16_t *)m->data)[0] = htole16(m->offset | 0x8000);
+		count = m->offset + 2;
+	}
+
+	ret = write_retry(m->outfd, m->data, count);
+
+	if (ret < 0) {
+		perror("writing meta data");
+		return -1;
+	}
+
+	if (ret < count) {
+		fputs("meta data written to file was truncated\n", stderr);
+		return -1;
+	}
+
+	memset(m->data, 0, sizeof(m->data));
+	m->offset = 0;
+	m->block_offset += count;
+	return 0;
+}
+
+int meta_writer_append(meta_writer_t *m, const void *data, size_t size)
+{
+	size_t diff;
+
+	while (size != 0) {
+		diff = sizeof(m->data) - 2 - m->offset;
+
+		if (diff == 0) {
+			if (meta_writer_flush(m))
+				return -1;
+			diff = sizeof(m->data) - 2;
+		}
+
+		if (diff > size)
+			diff = size;
+
+		memcpy(m->data + 2 + m->offset, data, diff);
+		m->offset += diff;
+		size -= diff;
+		data = (const char *)data + diff;
+	}
+
+	if (m->offset == (sizeof(m->data) - 2))
+		return meta_writer_flush(m);
+
+	return 0;
+}